cbc.c revision 1.9
1 /* $NetBSD: cbc.c,v 1.9 1995/03/21 09:04:36 cgd Exp $ */ 2 3 /* cbc.c: This file contains the encryption routines for the ed line editor */ 4 /*- 5 * Copyright (c) 1993 The Regents of the University of California. 6 * All rights reserved. 7 * 8 * Copyright (c) 1993 Andrew Moore, Talke Studio. 9 * All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 * 39 * from: @(#)bdes.c 5.5 (Berkeley) 6/27/91 40 */ 41 42 #ifndef lint 43 #if 0 44 static char *rcsid = "@(#)cbc.c,v 1.2 1994/02/01 00:34:36 alm Exp"; 45 #else 46 static char rcsid[] = "$NetBSD: cbc.c,v 1.9 1995/03/21 09:04:36 cgd Exp $"; 47 #endif 48 #endif /* not lint */ 49 50 #include <sys/types.h> 51 #include <ctype.h> 52 #include <errno.h> 53 #include <pwd.h> 54 55 #include "ed.h" 56 57 58 /* 59 * Define a divisor for rand() that yields a uniform distribution in the 60 * range 0-255. 61 */ 62 #define RAND_DIV (((unsigned) RAND_MAX + 1) >> 8) 63 64 /* 65 * BSD and System V systems offer special library calls that do 66 * block move_liness and fills, so if possible we take advantage of them 67 */ 68 #define MEMCPY(dest,src,len) memcpy((dest),(src),(len)) 69 #define MEMZERO(dest,len) memset((dest), 0, (len)) 70 71 /* Hide the calls to the primitive encryption routines. */ 72 #define DES_KEY(buf) \ 73 if (des_setkey(buf)) \ 74 des_error("des_setkey"); 75 #define DES_XFORM(buf) \ 76 if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \ 77 des_error("des_cipher"); 78 79 /* 80 * read/write - no error checking 81 */ 82 #define READ(buf, n, fp) fread(buf, sizeof(char), n, fp) 83 #define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp) 84 85 /* 86 * some things to make references easier 87 */ 88 typedef char Desbuf[8]; 89 #define CHAR(x,i) (x[i]) 90 #define UCHAR(x,i) (x[i]) 91 #define BUFFER(x) (x) 92 #define UBUFFER(x) (x) 93 94 /* 95 * global variables and related macros 96 */ 97 98 enum { /* encrypt, decrypt, authenticate */ 99 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE 100 } mode = MODE_ENCRYPT; 101 102 Desbuf ivec; /* initialization vector */ 103 Desbuf pvec; /* padding vector */ 104 char bits[] = { /* used to extract bits from a char */ 105 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001' 106 }; 107 int pflag; /* 1 to preserve parity bits */ 108 109 unsigned char des_buf[8]; /* shared buffer for get_des_char/put_des_char */ 110 int des_ct = 0; /* count for get_des_char/put_des_char */ 111 int des_n = 0; /* index for put_des_char/get_des_char */ 112 113 114 /* init_des_cipher: initialize DES */ 115 void 116 init_des_cipher() 117 { 118 #ifdef DES 119 int i; 120 121 des_ct = des_n = 0; 122 123 /* initialize the initialization vctor */ 124 MEMZERO(ivec, 8); 125 126 /* intialize the padding vector */ 127 srand((unsigned) time((time_t *) 0)); 128 for (i = 0; i < 8; i++) 129 CHAR(pvec, i) = (char) (rand()/RAND_DIV); 130 #endif 131 } 132 133 134 /* get_des_char: return next char in an encrypted file */ 135 int 136 get_des_char(fp) 137 FILE *fp; 138 { 139 #ifdef DES 140 if (des_n >= des_ct) { 141 des_n = 0; 142 des_ct = cbc_decode(des_buf, fp); 143 } 144 return (des_ct > 0) ? des_buf[des_n++] : EOF; 145 #endif 146 } 147 148 149 /* put_des_char: write a char to an encrypted file; return char written */ 150 int 151 put_des_char(c, fp) 152 int c; 153 FILE *fp; 154 { 155 #ifdef DES 156 if (des_n == sizeof des_buf) { 157 des_ct = cbc_encode(des_buf, des_n, fp); 158 des_n = 0; 159 } 160 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF; 161 #endif 162 } 163 164 165 /* flush_des_file: flush an encrypted file's output; return status */ 166 int 167 flush_des_file(fp) 168 FILE *fp; 169 { 170 #ifdef DES 171 if (des_n == sizeof des_buf) { 172 des_ct = cbc_encode(des_buf, des_n, fp); 173 des_n = 0; 174 } 175 return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF; 176 #endif 177 } 178 179 #ifdef DES 180 /* 181 * get keyword from tty or stdin 182 */ 183 int 184 get_keyword() 185 { 186 register char *p; /* used to obtain the key */ 187 Desbuf msgbuf; /* I/O buffer */ 188 189 /* 190 * get the key 191 */ 192 if (*(p = getpass("Enter key: "))) { 193 194 /* 195 * copy it, nul-padded, into the key area 196 */ 197 expand_des_key(BUFFER(msgbuf), p); 198 MEMZERO(p, _PASSWORD_LEN); 199 set_des_key(msgbuf); 200 MEMZERO(msgbuf, sizeof msgbuf); 201 return 1; 202 } 203 return 0; 204 } 205 206 207 /* 208 * print a warning message and, possibly, terminate 209 */ 210 void 211 des_error(s) 212 char *s; /* the message */ 213 { 214 (void)sprintf(errmsg, "%s", s ? s : strerror(errno)); 215 } 216 217 /* 218 * map a hex character to an integer 219 */ 220 int 221 hex_to_binary(c, radix) 222 int c; /* char to be converted */ 223 int radix; /* base (2 to 16) */ 224 { 225 switch(c) { 226 case '0': return(0x0); 227 case '1': return(0x1); 228 case '2': return(radix > 2 ? 0x2 : -1); 229 case '3': return(radix > 3 ? 0x3 : -1); 230 case '4': return(radix > 4 ? 0x4 : -1); 231 case '5': return(radix > 5 ? 0x5 : -1); 232 case '6': return(radix > 6 ? 0x6 : -1); 233 case '7': return(radix > 7 ? 0x7 : -1); 234 case '8': return(radix > 8 ? 0x8 : -1); 235 case '9': return(radix > 9 ? 0x9 : -1); 236 case 'A': case 'a': return(radix > 10 ? 0xa : -1); 237 case 'B': case 'b': return(radix > 11 ? 0xb : -1); 238 case 'C': case 'c': return(radix > 12 ? 0xc : -1); 239 case 'D': case 'd': return(radix > 13 ? 0xd : -1); 240 case 'E': case 'e': return(radix > 14 ? 0xe : -1); 241 case 'F': case 'f': return(radix > 15 ? 0xf : -1); 242 } 243 /* 244 * invalid character 245 */ 246 return(-1); 247 } 248 249 /* 250 * convert the key to a bit pattern 251 */ 252 void 253 expand_des_key(obuf, ibuf) 254 char *obuf; /* bit pattern */ 255 char *ibuf; /* the key itself */ 256 { 257 register int i, j; /* counter in a for loop */ 258 int nbuf[64]; /* used for hex/key translation */ 259 260 /* 261 * leading '0x' or '0X' == hex key 262 */ 263 if (ibuf[0] == '0' && (ibuf[1] == 'x' || ibuf[1] == 'X')) { 264 ibuf = &ibuf[2]; 265 /* 266 * now translate it, bombing on any illegal hex digit 267 */ 268 for (i = 0; ibuf[i] && i < 16; i++) 269 if ((nbuf[i] = hex_to_binary((int) ibuf[i], 16)) == -1) 270 des_error("bad hex digit in key"); 271 while (i < 16) 272 nbuf[i++] = 0; 273 for (i = 0; i < 8; i++) 274 obuf[i] = 275 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf); 276 /* preserve parity bits */ 277 pflag = 1; 278 return; 279 } 280 /* 281 * leading '0b' or '0B' == binary key 282 */ 283 if (ibuf[0] == '0' && (ibuf[1] == 'b' || ibuf[1] == 'B')) { 284 ibuf = &ibuf[2]; 285 /* 286 * now translate it, bombing on any illegal binary digit 287 */ 288 for (i = 0; ibuf[i] && i < 16; i++) 289 if ((nbuf[i] = hex_to_binary((int) ibuf[i], 2)) == -1) 290 des_error("bad binary digit in key"); 291 while (i < 64) 292 nbuf[i++] = 0; 293 for (i = 0; i < 8; i++) 294 for (j = 0; j < 8; j++) 295 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j]; 296 /* preserve parity bits */ 297 pflag = 1; 298 return; 299 } 300 /* 301 * no special leader -- ASCII 302 */ 303 (void)strncpy(obuf, ibuf, 8); 304 } 305 306 /***************** 307 * DES FUNCTIONS * 308 *****************/ 309 /* 310 * This sets the DES key and (if you're using the deszip version) 311 * the direction of the transformation. This uses the Sun 312 * to map the 64-bit key onto the 56 bits that the key schedule 313 * generation routines use: the old way, which just uses the user- 314 * supplied 64 bits as is, and the new way, which resets the parity 315 * bit to be the same as the low-order bit in each character. The 316 * new way generates a greater variety of key schedules, since many 317 * systems set the parity (high) bit of each character to 0, and the 318 * DES ignores the low order bit of each character. 319 */ 320 void 321 set_des_key(buf) 322 Desbuf buf; /* key block */ 323 { 324 register int i, j; /* counter in a for loop */ 325 register int par; /* parity counter */ 326 327 /* 328 * if the parity is not preserved, flip it 329 */ 330 if (!pflag) { 331 for (i = 0; i < 8; i++) { 332 par = 0; 333 for (j = 1; j < 8; j++) 334 if ((bits[j]&UCHAR(buf, i)) != 0) 335 par++; 336 if ((par&01) == 01) 337 UCHAR(buf, i) = UCHAR(buf, i)&0177; 338 else 339 UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200; 340 } 341 } 342 343 DES_KEY(UBUFFER(buf)); 344 } 345 346 347 /* 348 * This encrypts using the Cipher Block Chaining mode of DES 349 */ 350 int 351 cbc_encode(msgbuf, n, fp) 352 char *msgbuf; 353 int n; 354 FILE *fp; 355 { 356 int inverse = 0; /* 0 to encrypt, 1 to decrypt */ 357 358 /* 359 * do the transformation 360 */ 361 if (n == 8) { 362 for (n = 0; n < 8; n++) 363 CHAR(msgbuf, n) ^= CHAR(ivec, n); 364 DES_XFORM(UBUFFER(msgbuf)); 365 MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8); 366 return WRITE(BUFFER(msgbuf), 8, fp); 367 } 368 /* 369 * at EOF or last block -- in either case, the last byte contains 370 * the character representation of the number of bytes in it 371 */ 372 /* 373 MEMZERO(msgbuf + n, 8 - n); 374 */ 375 /* 376 * Pad the last block randomly 377 */ 378 (void)MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n); 379 CHAR(msgbuf, 7) = n; 380 for (n = 0; n < 8; n++) 381 CHAR(msgbuf, n) ^= CHAR(ivec, n); 382 DES_XFORM(UBUFFER(msgbuf)); 383 return WRITE(BUFFER(msgbuf), 8, fp); 384 } 385 386 /* 387 * This decrypts using the Cipher Block Chaining mode of DES 388 */ 389 int 390 cbc_decode(msgbuf, fp) 391 char *msgbuf; /* I/O buffer */ 392 FILE *fp; /* input file descriptor */ 393 { 394 Desbuf ibuf; /* temp buffer for initialization vector */ 395 register int n; /* number of bytes actually read */ 396 register int c; /* used to test for EOF */ 397 int inverse = 1; /* 0 to encrypt, 1 to decrypt */ 398 399 if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) { 400 /* 401 * do the transformation 402 */ 403 MEMCPY(BUFFER(ibuf), BUFFER(msgbuf), 8); 404 DES_XFORM(UBUFFER(msgbuf)); 405 for (c = 0; c < 8; c++) 406 UCHAR(msgbuf, c) ^= UCHAR(ivec, c); 407 MEMCPY(BUFFER(ivec), BUFFER(ibuf), 8); 408 /* 409 * if the last one, handle it specially 410 */ 411 if ((c = fgetc(fp)) == EOF) { 412 n = CHAR(msgbuf, 7); 413 if (n < 0 || n > 7) { 414 des_error("decryption failed (block corrupted)"); 415 return EOF; 416 } 417 } else 418 (void)ungetc(c, fp); 419 return n; 420 } 421 if (n > 0) 422 des_error("decryption failed (incomplete block)"); 423 else if (n < 0) 424 des_error("cannot read file"); 425 return EOF; 426 } 427 #endif /* DES */ 428
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